Powertrain, generic · Fuel and air metering (injector circuit)
P02CA Turbocharger/Supercharger B Overboost Condition
Check engine lightOn
EmissionsRelevant
Drive cycleRequired
Limp modePossible
Turbocharger B is a second, separately controlled turbo – on twin-turbo or two-stage systems, or one per bank. No manufacturer using the turbo B codes was found; twin-turbo engines such as GM's 3.0 V6 and Ford's 3.5 EcoBoost report boost faults under P0234/P0299 with a shared boost sensor, so the description follows CARB and the turbo A codes. P02CA means actual boost of turbo B stays above target although the control is already lowering it; for turbo A, GM petrol engines use 20–35 kPa, Ford EcoBoost more than 4 psi over 5 s. Boost is then limited.
Likely causes
Wastegate B stuck closed, linkage seized
Boost control valve or actuator B faulty, vacuum line swapped or leaking
Boost sensor reading wrong
Turbo B vanes sooted (diesel)
Software or calibration, tuning
Symptoms
- Check engine light, reduced power, limp mode
- Power cut under load
- Possibly knocking (petrol)
Repair estimate
DifficultyHardWorkshop job
Parts and labour€150–1,800
Time1–6 h
Typical range across vehicles; the real cost depends on what the testing finds.
Parts involved
turbocharger bwastegate bboost control valve
Related codes
References: law.cornell.edu, gsi.ext.gm.com, fordservicecontent.com.